Lyons used LEO initially for “Bakery Valuation,” computing the cost of goods and profit margin. The company later added payroll, inventory, invoices, and scheduling duties. But after hours, LEO did secret ballistics calculations for the government.

Operators used these displays to monitor the computer’s operation. This tube is from the third LEO II built (one of the first installed outside of Lyons). The computer was used by prominent British steelmaker Stewart & Lloyds for payroll processing.